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Hank F.
Hank F., RV tech - emphasis on gensets
Category: RV
Satisfied Customers: 14989
Experience:  RV tech since the beginning of the millenium.
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I have a onan 5.5 hgjab that has been giving me issues I

Customer Question

I have a onan 5.5 hgjab that has been giving me issues I cleaned the carb the only gas that runs in the generator is ethanol free. It will start run and idle fine.  Starts to sound ruff with the AC on IF I turn on the microwave or the electric water heater on with a load after about a 35 seconds it shuts off . how do I Test the frequency or governor.

Submitted: 2 years ago.
Category: RV
Expert:  Hank F. replied 2 years ago.
My name is ***** ***** I am going to assist you with this.

What is the full model number of the genset, exactly like it is written on the data label?
What fault code is the controller putting out?

Go to the genset and use the switch on the set itself.
Press 'Stop' 3 times within 5 seconds. The light in the switch will start flashing.
If the light flashes 3 times, pauses for 3 seconds, and flashes 3 more times, press and immediately release 'Stop' one more time.

This will put the controller into Fault Read Mode.

The light will flash (X) number of times, pause for 1 second, and flash for (X) number of times again. Count the flashes before and after the pause.

This will be the Fault Code.

Example: 2 rapid flashes, 1 second pause, 5 rapid flashes is a Fault Code 25.

There may be more than one Fault Code stored, so watch the light very carefully. If there is more than one code, it will display them all in order, and then start over again.

Be very careful not to misread a first level fault code (single digit code) as a second level fault code (double digit code).

The way to tell the difference is by the length of the pauses.

There is a 1 second pause between digits of a second level code, and a 3 second pause between codes.

For example, if it is flashing 2 times, 1 second pause, flashing 2 times, 3 second pause and repeating, then this is a second level fault code of 22.

If it is flashing 2 times, 3 second pause, flashing 2 times, 3 second pause and repeating, then this is a first level fault code of 2.

What Fault Code are you getting?


Customer: replied 2 years ago.

It's late for me to check that out tonight I will get you the info in morning thanks for getting back to me

Expert:  Hank F. replied 2 years ago.
Tomorrow is fine.
Sorry it took so long to reply, but I work 2 jobs, and help on Just Answer in the evenings.
Tomorrow through Tuesday, I work my factory job, 7AM to 7PM, so will not be able to respond until at least 7:30PM EST.
Customer: replied 2 years ago.

The exact model is 5.5HGJAB -1038D the only fault code I saw was a 15 . I ran it for about 8 minutes with the AC on high (just one unit) then turned on the water heater gave it another 5 minutes and of course it did not shut I turned the microwave on the generator made some more sound like it was doing more work then about 30 seconds later it shut down with that code. It definitely takes time after it warms up.

Expert:  Hank F. replied 2 years ago.
This is an older version of the HGJAB,

Code 15 is Under Frequency. It means that the engine is running too slow.

To test the actual frequency, just connect a frequency meter across one of the hot legs and neutral at the AC output leads, and start the genset. Read frequency with no load on it.

But I can tell you that the code 15 is caused by a bad carburetor.

As gas gets old, it turns to varnish and clogs up the passageways inside the carburetor, not allowing enough gas to get to the engine.

This condition is cumulative. Every time gas sits, the varnish builds up just a little more, like coats of paint, until eventually gas can not flow. It will not happen overnight, but the symptoms can show up all of a sudden, even while simply stopping to refill with gas.

The use of fuel additives, such as Sta-Bil or Sea Foam will not stop this process from happening. They will greatly slow it down, but the gas will still go bad.

When this happens, either the engine simply will not start, or it will not run without the choke on (this reduces the amount of air getting pulled into the engine, changing the fuel/air mixture), or it will run but surges.

Another issue that varnish in the carb can cause is that the varnish may not allow the float needle to seal properly against the seat, causing the flow of gas to not shut off when the bowl is full. The result will be gas overflowing the carb and running into the cylinder, and possibly out the air intake. If the gas gets into the cylinder, it will seep past the rings and down into the crankcase. This will be evidenced by your oil level being over-full and/or the oil smelling like gas.

If this is the case, you will need to change the oil and filter, if it has a filter.

The only 2 solutions are to either replace the carburetor or give it a good, thorough cleaning.

When removing the carb, make sure to take a good picture, or make a good drawing of where all springs and linkages are attached. This will make reassembly much easier.

Most people believe that cleaning a carb involves removing the bowl and wiping it out, then spraying some carb cleaner through it.

This is simply insufficient. It takes months or years for this accumulation to build up – it just can not be removed in minutes.

To properly clean the carb, you must remove it, disassemble it (making sure to remove all non-metal parts), and soak it in a commercial solvent for several hours. Soaking it overnight is even better.

Then clean all solvent off with a spray type carb cleaner, making sure to get lots of cleaner into every hole and passage there is. Pay special attention to the tiny holes in the bore of the carb, under the throttle plate for the carbs that have these holes. Use lots of cleaner. And make sure to wear safety goggles to avoid getting the over spray into your eyes. There will be over spray.

Dry the carb with low pressure compressed air.

This is an EPA compliant carburetor, and as such, is not supposed to be taken apart or adjusted.

When you have an issue with it, you are supposed to replace the entire carb.

But, sometimes it is possible to clean them. Just remember, that as an EPA compliant carb, there are no parts available for it, so if you lose or break anything, you will definitely need to get a new one.

Occasionally, even a good cleaning is not going to be sufficient, and you may end up having to replace the carb anyhow. Be prepared for this.

I personally do not recommend cleaning of this carb. It is extremely sensitive, and cleaning rarely works.
Customer: replied 2 years ago.

OK I have a brand new carb that I bought last year in case that was the problem. I was hoping a good cleaning would work I actually did clean the carb like you advised. I been messing with small carbs for years due to riding ATV's and Dirt Bikes and I was always successful at cleaning them. I will install the carb tomorrow and let you know

Expert:  Hank F. replied 2 years ago.
to try and clean these carbs, to save my customers some money.
But even with an ultra sonic cleaner, the failure rate was so high, that I quit even trying. By the time I figured in my labor, it ended up costing the customer more than just replacing it.
Customer: replied 2 years ago.

I replaced the carb today with the new one everything was installed the same and it still cut out with a 15 code with Access on high water heater on and the microwave running. Any other suggestions

Expert:  Hank F. replied 2 years ago.
When you installed the carb, and connected the throttle link to the governor arm, did you make sure that little blue plastic bushing got put back in?

Have you been tinkering with the governor at all?
Customer: replied 2 years ago.

Yes that's in place I have not messed with anything mechanical or the adjust the spring I would like to mention when I first was running everything it popped the top 30amp break.

Expert:  Hank F. replied 2 years ago.
The breaker has nothing to do with the genset staying running. It only has to do with the load that the genset is trying to push.

When the gen is running, does it run steady and smooth, or does it surge?
What frequency reading do you get with no load on the genset?